Atomic Self-diffusion in Quasicrystals
نویسنده
چکیده
A molecular dynamics study on atomic self-diffusion in Frank-Kasper type dodecagonal quasicrystals is presented. It is found that the quasicrystal-specific flip mechanism for atomic diffusion, predicted by Kalugin and Katz, indeed occurs in this system. However, in order to be effective, this mechanism needs to be catalyzed by other defects, such as half-vacancies. For this reason, flip diffusion is difficult to distinguish from standard vacancy diffusion.
منابع مشابه
Atomic dynamics and diffusion in decagonal quasicrystals
The atomic dynamics of decagonal Al-Ni-Co and Al-Cu-Co quasicrystals is investigated by molecular dynamics simulations. Depending on the local environments, the mobility of the atoms varies greatly from site to site. Above two thirds of the melting temperature, a large fraction of the aluminium atoms become so mobile, that their diffusion can be measured directly in the simulation. As aluminium...
متن کاملAtomic Dynamics in Decagonal Al-Ni-Co Quasicrystals
The atomic dynamics of decagonal Al-Ni-Co quasicrystals is investigated by molecular dynamics simulations. The model structures used consist of an alternating stacking of two layers, which are decorations of a hexagon-boat-star tiling. Apart from small relaxations, these model structures are essentially stable up to the melting point. Above two thirds of the melting temperature, a large fractio...
متن کاملMn Self-Diffusion in Single Grain Icosahedral Al70Pd21.5Mn8.5 Quasicrystals.
The self-diffusivity of 54Mn in single grain icosahedral Al70Pd21.5Mn8.5 quasicrystals has been determined by a precision grinding technique. In the range from 870 to 1093 K the temperature dependence of the Mn selfdiffusivity D follows the Arrhenius equation with an activation energy Q = (180.8±4.6)kJmol-1 and a preexponential factor D0 = 3.4×10-4m2s-1. The experimental results are discussed t...
متن کاملSelf-diffusion in random-tiling quasicrystals.
The first explicit realization of the conjecture that phason dynamics leads to self-diffusion in quasicrystals is presented for the icosahedral Ammann tilings. On short time scales, the transport is found to be subdiffusive with the exponent β ≈ 0.57(1), while on long time scales it is consistent with normal diffusion that is up to an order of magnitude larger than in the typical room temperatu...
متن کاملStability of quasicrystals composed of soft isotropic particles
Quasicrystals whose building blocks are of mesoscopic rather than atomic scale have recently been discovered in several soft-matter systems. Contrary to metallurgic quasicrystals whose source of stability remains a question of great debate to this day, we argue that the stability of certain soft-matter quasicrystals can be directly explained by examining a coarse-grained free energy for a syste...
متن کامل